Hair relaxer compositions and methods for preparing same

ABSTRACT

Methods for preparing hair relaxer compositions which comprise a lithium salt and an alkaline earth hydroxide, wherein the lithium salt is in molar excess to the alkaline earth hydroxide. Compositions, kits containing the compositions, and methods for using the compositions are also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention involves the art of straightening of kinky hair by alithium relaxer which is made by a novel process.

2. Description of Related Art

Hair relaxer (straightener) compositions presently known to the art arehighly alkaline, oil-in-water emulsions which derive their chemicalreactivity from either (1) alkali metal hydroxides, (2) quaternaryammonium hydroxides, or (3) guanidinium hydroxide dissolved or suspendedin the water phase of these hair-treatment formulations such that the pHvalues of these emulsions are in the range of from 12 to 14. Among thoseskilled in the art, it is widely and generally accepted that it is thehydroxide ion, which is the alkaline chemical species common to allthree of the above classes, that is the essential active ingredient inthese "strong-base" relaxers. In fact, it has be firmly proven that,when inside the cortex of the hair, hydroxide ions readily abstractacidic alpha protons from the cysteine moieties of hair keratin leadingto reversible beta elimination of alkyl disulfide (opening ofcrosslinks) with the concomitant formation of dehydroalanine. It is asthese crosslinks continuously open and reform that kinky hair, undermechanical stress, is relaxed to a permanently straight configuration.

Although it is the hydroxide anion which is responsible for initiatingthe chemical reactions within the hair shaft which lead tostraightening, it is the cation with which the hydroxide is associatedthat has distinguished among the various relaxer types. Prior to 1979,only those one-component ("no-mix") hair relaxer compositions derivingfrom either sodium or potassium hydroxides were known. In 1979, CarsonProducts Company (U.S. Pat. No. 4,304,244) introduced the mix type"no-lye" relaxers containing guanidinium hydroxide. Because guanidiniumhydroxide is not stable for long periods in aqueous solutions, it mustbe prepared fresh just before using. Guanidinium hydroxide is generallyprepared by mixing an inorganic alkaline earth hydroxide with an aqueoussolution of a salt of the strong organic base guanidine, where the anionof this salt is capable of being precipitated by the cation of thealkaline earth hydroxide. In commercially available products of thistype, the guanidinium hydroxide is generally prepared using calciumhydroxide and guanidine carbonate.

There are presently two principal defects in all of the prior art hairrelaxers. These are as follows: (1) because of their high alkalinity,all can potentially cause scalp irritation and/or injury during therelaxing treatment; and (2) because all are strong-base relaxers capableof dissolving hair keratin, all can overprocess the hair causingirreversible damage to the fibrous keratin structure leading to hairbreakage. It has been a continuing goal of researchers in this industryto correct these serious defects.

The scalp irritation potential of chemical relaxers has been reducedsomewhat through the formulation of better and better cosmetic emulsionscontaining high levels of skin-protecting oils such as petrolatum andmineral oil. And, most importantly, it was discovered that relaxersderiving from guanidinium hydroxide are inherently less irritating tothe skin and scalp than those deriving from the alkali metal hydroxides.Significantly reducing the irritation potential of hair relaxers,however, remains a major technical challenge to relaxer formulators.

The problem of overprocessing is manifest in the strong-base chemistryof these formulations. With strong bases which are capable of totallydissolving hair, the only control a formulator has in designing saferrelaxers is to adjust the concentration of the active ingredient to anoptimally effective level. Then, it is up to the user to carefully timethe treatment and stop the process when the hair is straight and beforeit is damaged. Salon professionals learn these skills through training,while consumers of home-use, kit-type relaxers learn through trial anderror.

Like sodium and potassium hydroxides, lithium hydroxide is also analkali metal hydroxide, and indeed in the 1980s lithium hydroxide wasused to formulate commercially successful hair relaxers of the "no-mix"type. Interestingly, those skilled in the relaxer art now make no realdistinction among sodium, potassium, and lithium hydroxides as isattested to in the following excerpt from a recent relaxer patentspecification (Akhtar et al., U.S. Pat. No. 4,950,485, col 7, in 16):"Alternatively, a cosmetic cream base for use directly as a no-base hairrelaxing composition can contain a water-soluble alkaline causticmaterial which is capable of both bringing the pH of the composition toa value of about 12 to about 14, and acting as the sole hair relaxingagent. Alkali metal hydroxides, including sodium hydroxide, potassiumhydroxide and lithium hydroxide may be used as the water-solublealkaline caustic material. Sodium hydroxide is preferred and may bepresent in amounts from about 1 to about 3 weight percent of the totalcomposition, preferably from about 1.5 to 2.5 weight percent."

Unlike sodium and potassium hydroxides, however, an aqueous solution oflithium hydroxide is reportedly a "weak electrolyte" (lower electricalconductance), which is evidence of incomplete ionization, which in turndefines lithium hydroxide as a classical "weak base'. Commercial hairrelaxers made with lithium hydroxide as the active ingredient typicallyhave pH values of around 12.2 to 12.7; whereas, those made with sodiumhydroxide or guanidinium hydroxide generally exceed 13.5. This being thecase, one can only guess the answers to the following two questions--(1)If indeed, the hydroxide anion is the species solely responsible for thechemical reactivity of hair relaxer formulations, how can a lithiumhydroxide relaxer having a hydroxide ion concentration which is lower bya factor of at least 10 be just as effective in straightening hair as asodium hydroxide or guanidinium hydroxide relaxer? (2) If the pH issignificantly lower, why does the incidence of skin and scalp irritationexperienced by users of lithium hydroxide relaxers equal or exceed thatof sodium hydroxide relaxer users?

In an attempt to answer the two questions posed above, a search of thetechnical literature was conducted to locate a value for thedissociation constant for lithium hydroxide: ##STR1##

One reference (Darken and Meier) reported K=1.2 based on electricalconducted. Surprisingly, when used to solve Eq. 1, the literature valueof K did not predict the pH of lithium hydroxide relaxers (usually about12.6). Moreover, it did not predict the pH of simple solutions oflithium hydroxide prepared in the laboratory. For example, the aqueousphase of a typical relaxer is about 1 molar in lithium hydroxide. Avalue for K_(x) of 1.2 predicts that the pH would be 13.72. When 1 molarlithium hydroxide solutions were prepared in the laboratory, the pH was13.01. Because the relationship between the pH and the hydroxideconcentration of a solution is exponential, a discrepancy in pH of +0.71of a pH unit represents nearly a 6-fold difference in predicted vs.experimental molar hydroxide concentration.

One explanation for this very large experimental discrepancy is that thevalue of K=1.2 (based on electrical conductivity) of lithium hydroxidesolutions describes something other that the simple dissociation of LiOHinto Li⁺ and OH⁻ ions.

Although lithium is classified in the periodic chart as an alkali metal,in many respects it is grossly different from sodium and/or potassium.In fact, in all salt-forming reactions, the "ionic" bonds betweenlithium and oxygen (and other electron-rich atoms) are so strong thatthese salt bonds behave to a large extent like covalent bonds ratherthan ionic bonds. For example, lithium stearate (an "alkali metal soap")is only minimally soluble in water; whereas the sodium and potassiumstearates are highly soluble. Lithium carbonate is soluble in water onlyup to about 1.5 gm per 100 gm of water, while sodium and potassiumcarbonates are extremely water soluble.

If the Li-O bond of LiOH is more like a covalent bond than an ionic one,then a secondary equilibrium can be established whereby hydroxide ionsabstract protons from undissociated LiOH molecules to produce a LiO⁻species (lithoate) according to the following equation: ##STR2##

Allowing for the formation of LiO⁻ according to Eq. 2 and combining Eq.1 with Eq. 2, the following can describe the dissociation of LiOH.##STR3##

An assumption can be made that Eq. 3 (not Eq. 1) now describes asolution of lithium hydroxide in water and that K_(xy) is thedissociation constant determined by Darken and Meier to have a value of1.2. Based on this assumption, numerical values for K_(x) and K_(y) canbe calculated to be 0.263 and 17.35, respectively. When thesedissociation constants were used to calculate the pH of aqueoussolutions that were 1 molar in lithium hydroxide, the equationspredicted that the pH was 12.99, which agreed well with the experimentdetermined value of 13.01. The complete description of all of thesoluble species in a 1 molar lithium hydroxide solution is as follows:

OH⁻ =0.143 molar

LiO⁻ =0.357 molar

LiOH=0.144 molar

Li⁺ =0.499 molar

pH=12.99

The 1 molar lithium hydroxide solution described above should becompared to an analogous 1 molar sodium hydroxide solution whose solublespecies are as follows:

OH⁻ =0.804 molar

NaOH=0.195 molar

Na⁺ =0.804 molar

pH=13.74

Clearly, the concentration of hydroxide ion in a 1 molar lithiumhydroxide solution is lower by a factor of more than 5 than thehydroxide concentration of an analogous sodium hydroxide solution.Chemists skilled in the art of hair relaxer formulations would certainlyagree that if one made a sodium hydroxide relaxer whose aqueous phasecontained only 0.143 molar NaOH (0.3 wt. % in the formula), a relaxer soweak would take many hours to relax hair. This being the case, it islikely that the LiO⁻ (lithoate) species, a base other than hydroxide, isthe principal active ingredient in lithium hydroxide relaxers.

In a number of applications-oriented studies, lithium hydroxide has beenobserved to behave differently than sodium hydroxide and/or potassiumhydroxide. For example, lithium hydroxide is sometimes used in thetanning of hides. It is reported to be absorbed into the skins to agreater extent than other alkalis, but it causes less swelling. Becausefrom a chemical viewpoint, hair keratin and skin keratin are verysimilar, one might expect lithium hydroxide (possibly as lithoate ion)to penetrate the hair shaft more readily and with less swelling thanother alkalis. This being the case, one would predict that lithiumhydroxide might be a good hair relaxer even though it has asubstantially lower hydroxide ion concentration than other types ofalkaline relaxers. Moreover, if lithium hydroxide is absorbed readilyinto animal hides, it might be expected to be absorbed readily into thehuman skin and scalp; thus, it might be highly irritating to the skineven thought the pH is lower than with other alkalis.

When lithium hydroxide relaxers are made in a manner and by a processanalogous to the preparation of sodium hydroxide relaxers, the skin andscalp irritation potential of the resulting emulsions is very high. Theincidence of caustic burning is much greater than for sodium hydroxiderelaxers having comparable molar concentrations of hydroxide ion.Skilled formulators, however, have discovered that the addition ofseveral percent of calcium oxide or calcium hydroxide to the lithiumhydroxide relaxer formulations somehow attenuates the activity of theactive chemical species with regard to skin and scalp irritation withoutcompromising hair straightening efficacy. The precise mechanism by whichcalcium hydroxide and/or calcium ions change the composition is notknown, but we can postulate that calcium hydroxide may cause some sortof shift in the chemical equilibrium causing a change in theconcentration of one or more of the active species.

With this improvement in the composition of lithium hydroxide relaxers,irritation is lessened to a measurable degree in most batches, but theproduction process is not highly reproducible and the results in thisregard are unpredictable. Many batches still have a very high potentialfor skin irritation and others have a much lower potential. It has beengenerally observed that those lithium hydroxide relaxer batches having ahigh propensity for skin irritation become somewhat milder and lessirritating with aging, but the aging time must be on the order of manymonths or several years. This suggests that lithium hydroxide (withcalcium hydroxide) relaxers made by present formulation processes do notquickly and reproducibly reach a thermodynamically stable state.Whatever the reason for the variability and unpredictability of presentlithium hydroxide relaxers, these relaxers have achieved far lesscommercial success than the sodium hydroxide relaxers and theguanidinium hydroxide relaxers.

SUMMARY OF THE INVENTION

The present invention provides compositions and methods for thepreparation of certain hair relaxers formulations, which formulationsderive their chemical activity from basic and alkaline salts of thealkali metal lithium, and which compositions also require the presenceof a partially soluble salt of lithium and a polyvalent anion such ascarbonate, sulfate, or phosphate. A process of the present inventioncomprises contacting a lithium salt (other than lithium hydroxide) withan alkaline earth hydroxide, wherein the anion of the lithium salt iscapable of being precipitated by the cation of the alkaline earthhydroxide. Thus, this invention addresses and describes a reactiveprocess for preparing "lithoate" hair relaxers having a very lowpotential for skin irritation and a very high degree of efficacy withregard to the straightening of curly and/or kinky hair.

The present invention can be considered an improvement over prior artcompositions and processes for preparing hair relaxers deriving theirchemical reactivity from "lithium hydroxide". The improvement comprises;(1) compositions which contain both "lithium hydroxide" and the lithiumsalt of a polyvalent anion, and/or (2) the use of a reactive mixture ofcertain lithium salts and hydroxide salts to prepare the aqueous phaseof oil-in-water emulsions such that the compositions and productsproduced by the process have a low degree of skin irritation from theoutset.

It has been found (in a preferred embodiment of this invention) thatemulsions prepared using an excess of lithium carbonate and a limitedamount of calcium hydroxide as reactive ingredients (instead of theusual lithium hydroxide and calcium oxide) are highly reproducible,highly effective hair relaxer formulations having a very low potentialfor causing skin irritation during the timeframe (usually no more than30 minutes) of a traditional relaxer treatment application. Moreover,unlike virtually all prior-art relaxers, the relaxers prepared accordingto this invention do not totally break down and dissolve hair;therefore, they do not cause or contribute to hair damage and breakagewhen used.

One skilled in the art will note that the compositions of the presentinvention may also be used in permanent wave or curling applications. Inthese latter applications the same advantages are seen as with thestraightening process, that is the compositions are effective and causeless irritation than the prior art compositions. Any conventional hairrelaxing or hair curling formulation may be used with the substitutionof the lithium salt and the alkaline earth hydroxide of the presentinvention for the active ingredients of the conventional formulation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred embodiment of the process of this invention, an excess ofan appropriately selected lithium salt and a predetermined amount of anappropriately selected alkaline earth hydroxide are mixed into theaqueous phase of an appropriately formulated oil-in-water emulsion. Achemical reaction immediately ensues whereby an insoluble salt of thecation of the alkaline earth hydroxide and the anion of the lithium saltprecipitates producing an alkaline aqueous phase mostly composed of asolution of soluble ionic and non-ionic lithium compounds.

In a most preferred embodiment of the invention, the lithium salt willbe lithium carbonate or lithium sulfate, and the alkaline earthhydroxide will be calcium hydroxide, barium hydroxide, or strontiumhydroxide. An appropriate oil-in-water emulsion is an emulsion known tothose skilled in the art as acceptable as a cosmetic or hair treatingcomposition. Such compositions may include conventional additives usedto provide their ordinary functions. In the most preferred embodiment,the lithium salt is in molar excess of from about 0.01% to about 10%.

The invention can be practiced in at least three different modes. In thedescription of these modes which follows, the example of lithiumcarbonate is used to represent all of the lithium salts which work inthis process and calcium hydroxide is used to represent all of thealkaline earth hydroxides which work in this process.

In the first mode, the process can be used during batching operations tomanufacture one-component, "no-mix" hair relaxers which are highlystable to prolonged storage. In the second mode, calcium hydroxide canbe formulated into an emulsion in a manner identical to the preparationof relaxer creams for two-component, "mix-type", guanidinium hydroxiderelaxers and lithium carbonate can be packaged and/or formulated as anactivator for addition to the relaxer cream by the consumer just priorto the relaxer treatment. In the third mode, an excess of lithiumcarbonate can be formulated in a relaxer cream that does not contain anycalcium hydroxide, and calcium hydroxide can be packaged and/orformulated as an activator for mixing with the relaxer cream by theconsumer just prior to the relaxer treatment.

The chemical reactions which underlie the process of this invention arethose which are already known to be preferred methods for the synthesisof lithium hydroxide. For example, a simple laboratory mode ofpreparation is the double decomposition of lithium sulfate and bariumhydroxide solutions (Barnes, E., J.C.S., 1931, 2, 605-20).

    Li.sub.2 SO.sub.4 +Ba(OH).sub.2 →BaSO.sub.4 +2LiOH

If exactly equivalent quantities of lithium sulfate and barium hydroxideare used, a pure dilute solution of lithium hydroxide remains afterfiltration.

A widely used process for the commercial production of lithium hydroxideis the causticization of lithium carbonate with lime. The reactionproceeds according to the equation:

    Li.sub.2 CO.sub.3 +Ca(OH).sub.2 →CaCO.sub.3 +2LiOH

The reactants are slurried together in water and boiled. With a 5%excess of slaked lime present and sufficient water to give a finalconcentration of 0.3 lb/gal, the conversion is nearly complete. Theprecipitated chalk is allowed to settle, and the lithium hydroxidesolution is decanted. The solution is then evaporated and on coolingyields crystals of lithium hydroxide monohydrate (>99% purity). Themajor impurity in the product is lithium carbonate formed by theabsorption of carbon dioxide from the atmosphere.

Even though the chemical reactions of the preferred embodiment of thisinvention are those which are known to produce virtually quantitativeyields of "lithium hydroxides", it was totally unexpected to discoverthat, when freshly prepared, hair relaxer formulations containing"lithium hydroxides" prepared in situ were much less irritating thanhair relaxer formulations prepared with commercial lithium hydroxidemonohydrate, with or without added calcium oxide or calcium hydroxide.In preparing numerous relaxers using lithium carbonate and calciumhydroxide, it was subsequently discovered that those relaxers which wereprepared with an excess of the calcium hydroxide became more and moreirritating with the passage of several week's time, while those thatcontained an excess of the lithium carbonate did not become moreirritating.

The reasons for this difference are still not completely understood, butlaboratory evidence suggests that the difference is manifest in theinteraction of soluble yet unreacted polyvalent lithium salts and/ortheir polyvalent anions with one of the species in the followingequilibrium:

    3LiOH⃡2Li.sup.+ +OH.sup.- +LiO.sup.- +H.sub.2 O

Aside from the plethora of Li⁺ ions, which are undoubtedly intimatelyassociated with all anions, the most likely species to interact withpolyvalent anions is the undissociated (neutral) LiOH molecules.

Assuming that neutral LiOH interacts with either carbonate or sulfate,one may postulate the formation of complex species such as thefollowing: ##STR4##

The presence of such complexes in the compositions of the presentinvention would strongly suggest why these novel hair relaxers have sucha low propensity for irritating the skin and scalp. Consider thefollowing:

It is widely accepted that small neutral molecules penetrate the skinmore rapidly than solvated ions and intimate ion pairs. Considering thataqueous solutions of lithium hydroxide (and prior art hair relaxers madewith "lithium hydroxide") contain a relatively large fraction ofundissociated LiOH, one would expect that such solutions could have anabnormally high potential for irritating living skin tissues. On theother hand, if the undissociated LiOH molecules formed stable, largequasi-ionic complexes in the presence of polyvalent anions, one mightexpect that the irritation potential would be reduced substantially.

The reaction at room temperature of lithium carbonate with calciumhydroxide proceeds rapidly to about 60% of completion and then slowsdown considerably. Because lithium carbonate is about 10-times moresoluble than calcium hydroxide, freshly prepared relaxers of the presentinvention always contain lithium carbonate, regardless of whether or notan excess of calcium hydroxide is used. The presence of the carbonatemoiety could account for the low irritation potential of freshlyprepared relaxers. When an excess of calcium hydroxide is used, however,those relaxers eventually become totally depleted of lithium carbonateas the double decomposition reaction goes to completion. Such relaxersthen have a higher potential for irritating the skin and scalp. Thelength of time that it takes for such relaxers to become lithiumcarbonate depleted depends upon many variable such as the startingconcentrations of reactants, the storage temperature, and theconsistency (thin or thick) of the relaxer cream.

Unlike those hair relaxers prepared with commercial lithium hydroxide,the order of addition, the formulation/reaction time, and thetemperature are not critical parameters affecting the composition or theperformance of the relaxers of the present invention. For example, whenthe prior-art lithium hydroxide relaxers are prepared, care must betaken to ensure that all of the lithium hydroxide monohydrate iscompletely pre-dissolved in a portion of the water used to make theaqueous phase, that an excess of calcium oxide or calcium hydroxide isadded to the lithium hydroxide solution just prior to the addition ofthis portion to the formulation, and that the lithium hydroxide solution(with slurried lime) is added at about 65° C. after the oil-in-wateremulsion has been formed/phased at about 85° C. and the hot formulationis being cooled. In the process of the present invention, lithiumcarbonate and calcium hydroxide can be added to the aqueous portion ofthe formulation either at any time prior to heating the mixture to near85° C. for phasing or after the mixture has been phased and is cooling.Alternatively, either the lithium carbonate or the calcium hydroxidealone can be added to and/or formulated into the emulsion at any stageof the manufacturing process, and the other reactive component can beadded as an activator (by the consumer) at any time prior to use.

It should be stressed that it is not imperative that a reactive processutilizing certain polyvalent lithium salts and certain alkaline earthhydroxides be used to form the compositions of the present invention.Rather, certain polyvalent lithium salts, such as lithium carbonate andlithium sulfate, may be mixed directly with commercial lithium hydroxidein the aqueous phase of a suitable oil-in-water emulsion to yield hairrelaxers having a low potential for skin irritation. One skilled in theart might also prepare an alkaline aqueous solution (phase) containinglithium hydroxide and then press in some carbon dioxide to produce aneffective amount of lithium carbonate in situ.

The relaxer compositions of the present invention not only have a lowerpotential for causing skin and scalp irritation than prior art "lithiumhydroxide" relaxers, they also react differently with hair.

EXAMPLES

While not intended to be limiting in any way the scope of the presentinvention, the following examples demonstrate embodiments of the presentinvention.

Example 1 (Formula 2000)

This example illustrates the preparation of a one-component/no-mix haircream/emulsion. The formula is as follows:

    ______________________________________                                        Ingredients         Weight Percent                                            ______________________________________                                        Part A:                                                                       Polawax             8.00                                                      Cetyl Alcohol       0.50                                                      Stearyl Alcohol     0.30                                                      PEG-75 Lanolin      2.00                                                      Petrolatum          13.55                                                     Mineral Oil         18.01                                                     Laneth-15           0.40                                                      PEG-24 Hydrogenated Lanolin                                                                       0.20                                                      Ethoxylated Soya Sterol                                                                           2.00                                                      Part B:                                                                       Water               41.03                                                     Propylene Glycol    5.60                                                      Polyol Alkoxy Ester 1.00                                                      Oleth-3             0.30                                                      Lithium Carbonate   2.80                                                      Calcium Hydroxide   2.31                                                      Polyquaternium-2    2.00                                                      ______________________________________                                    

Process of making: All of the ingredients of the oil phase (Part A) aremixed in an appropriate stirred vessel and the mixture is heated to 85°C. All of the ingredients of the aqueous phase (Part B), except for thePolquaternium-2, are placed in a vessel outfitted with a homogenizermixer, and the mixture is heated, with stirring, to 85° C. When bothphases have reached their target temperatures, the hot oil phase (PartA) is added to the hot aqueous phase (Part B) and the two-phase ishomogenized at high speed for 15 minutes to form a uniformly dispersedoil-in-water emulsion. The emulsion is then cooled to 60° C., at whichpoint it is transferred to a scraper vessel where it is further cooledto 45° C. The Polyquaternium-2 is then added, and the finished cream iscooled to room temperature with slow agitation.

The pH of the finished product was 12.3.

The kinky hair of a Negro female was gently combed to remove tangles,and then the hair was parted into four quadrants. A generous amount ofthe relaxer formulation was applied to the hair on a section-by-sectionbasis. The hair was combed gently after the relaxer was applied toensure even distribution. When the entire head of hair appeared to becovered with the relaxer cream, the hair was parted with a comb indifferent sections of the head and checked to ensure that the relaxerformulation had penetrated to the hair root area. Thereafter, all of thehair was smoothed (i. e., straightened) frequently using hands or theback of a plastic comb until the desired degree of straightness wasachieved.

The hair was rinsed thoroughly with warm water until all of the relaxercream was removed. Then the hair was shampooed with a buffered, pH 5neutralizing shampoo, treated with a rinse-out protein conditioner,towelled dry, and set.

The hair treated with the formulation in this example had a permanentstraightening effect, which lasted until new growth appeared at the hairroots. Although this relaxer formulation touched the individual's scalpin numerous places for the duration of the treatment (about 20 minutes),there were no complaints of skin irritation and burning (a problem which"always" occurs when this individual uses most commercially availableproducts).

Example 2

This example demonstrates the preparation of a one-component/no-mix hairrelaxer/emulsion with about 10% faster reactivity with hair than thecomposition of Example 1. The formula is as follows:

    ______________________________________                                        Ingredients         Weight Percent                                            ______________________________________                                        Part A:                                                                       Polawax             8.00                                                      Cetyl Alcohol       0.50                                                      Stearyl Alcohol     0.30                                                      PEG-75 Lanolin      2.00                                                      Petrolatum          13.38                                                     Mineral Oil         17.32                                                     Laneth-15           0.40                                                      PEG-24 Hydrogenated Lanolin                                                                       0.20                                                      Ethoxylated Soya Sterol                                                                           2.00                                                      Part B:                                                                       Water               41.40                                                     Propylene Glycol    5.60                                                      Polyol Alkoxy Ester 1.00                                                      Oleth-3             0.30                                                      Lithium Carbonate   2.80                                                      Calcium Hydroxide   2.80                                                      Polyquaternium-2    2.00                                                      ______________________________________                                    

The process of making was exactly the same as in Example 1, and the pHof the finished product was 12.4.

Then this relaxer cream was applied to the hair of Negro women, theresults were the same as for Example 1 except the processing time wasabout 10% shorter for the same hair types (i.e., fine, medium, andcoarse).

Example 3

This example illustrates the preparation of a one-component/no-mix hairrelaxer cream/emulsion with about 10% faster reactivity with hair thanExample 2. The formula is as follows:

    ______________________________________                                        Ingredients         Weight Percent                                            ______________________________________                                        Part A:                                                                       Polawax             8.00                                                      Cetyl Alcohol       0.50                                                      Stearyl Alcohol     0.30                                                      PEG-75 Lanolin      2.00                                                      Petrolatum          13.30                                                     Mineral Oil         17.07                                                     Laneth-15           0.40                                                      PEG-24 Hydrogenated Lanolin                                                                       0.20                                                      Ethoxylated Soya Sterol                                                                           2.00                                                      Part B:                                                                       Water               43.00                                                     Propylene Glycol    5.60                                                      Polyol Alkoxy Ester 1.00                                                      Oleth-3             0.30                                                      Lithium Carbonate   3.30                                                      Calcium Hydroxide   2.83                                                      Hydroxypropyl       0.20                                                      Bis-stearyldimonium Chloride                                                  ______________________________________                                    

The process of making was the same as for Example 1, and the pH of thefinished product was 12.3.

When this relaxer cream was applied to the hair of Negro women, theresults were the same as for Example 2 except the processing time wasabout 10% shorter for the same hair types (i.e., fine, medium, andcoarse). Moreover, approximately one-tenth of all individuals on whomthis relaxer formulation was applied complained of mild to moderate skinand scalp irritation.

Example 4

This example represents the preparation of a two-component hair relaxerformulation containing Calcium Hydroxide in the relaxer base component(Component I) and Lithium Carbonate in the activator component(Component II).

    ______________________________________                                        Ingredients         Weight Percent                                            ______________________________________                                        Part A:                                                                       Polawax             8.00                                                      Catyl Alcohol       0.50                                                      Stearyl Alcohol     0.30                                                      PEG-75 Lanolin      2.00                                                      Petrolatum          15.78                                                     Mineral Oil         19.32                                                     Laneth-15           0.40                                                      PEG-24 Hydrogenated Lanolin                                                                       0.20                                                      Ethoxylated Soya Sterol                                                                           2.00                                                      Part B:                                                                       Water               45.40                                                     Polyol Alkoxy Ester 1.00                                                      Oleth-3             0.30                                                      Calcium Hydroxide   2.80                                                      Polyquaternium-2    2.00                                                      Component II:                                                                 Propylene Glycol    56.00                                                     Lithium Carbonate   40.00                                                     Fumed Silica        3.00                                                      Titanium Dioxide    1.00                                                      ______________________________________                                    

Process of making: Add Propylene Glycol to the kettle and begin moderateagitation with a high-speed Cowls disperser blade. Add Lithium Carbonateslowly until addition is complete. Continue disperser action and addFumed Silica and Titanium Dioxide. Continue mixing for 30 minutes.

An activated relaxer cream is prepared by mixing about 250 grams ofComponent I with 20 grams of Component II. Accurate measuring isrequired. The relaxer is ready to use in about 15 minutes after mixing.Moreover, the relaxer can be safely used without fear of irritation forat least one year after it is made. This is compared to thetwo-component relaxers deriving their activity from guanidine hydroxideof the prior art, which must be used within about four hours after theymixed.

Example 5

This example represents the preparation of a two-component hair relaxerformulation containing Lithium Carbonate in the relaxer base component(Component I) and Calcium Hydroxide in the activator component(Component II).

    ______________________________________                                        Component I                                                                   Ingredients        Weight Percent                                             ______________________________________                                        Part A:                                                                       Cosmowax J         10.50                                                      Petrolatum         10.75                                                      Mineral Oil        10.75                                                      Ethoxylated Soya Sterol                                                                          1.00                                                       Part B:                                                                       Water              59.69                                                      Lithium Carbonate  3.30                                                       PPG-12-PEG-65 Lanolin Oil                                                                        3.00                                                       Succinic Acid      0.25                                                       Part C:                                                                       PPG-B-Ceteth-10 Phosphate                                                                        1.50                                                       Part D:                                                                       Tropaeolin O       0.0015                                                     Water              0.0585                                                     ______________________________________                                    

Process of making: Add Part A ingredients to the homomixer kettle andbegin heating with moderate agitation to 80° C. Add Part B ingredientsto the scraper kettle and begin heating with moderate agitation to 80°C. When Part A and Part B reach 80° C., slowly add Part B to Part A andhomomix with moderate agitation for 15 minutes. Transfer batch back toscraper kettle and begin cooling with chilled water and moderate scraperagitation. When batch cools to 45° C., add Part C. Prepare Part D andadd it to the batch when the temperature reaches 40° C. Continue coolingto 33° C. Component I is pastel yellow in color and the pH is about 10.

    ______________________________________                                        Component II                                                                  Ingredients     Weight Percent                                                ______________________________________                                        Propylene Glycol                                                                              51.00                                                         Calcium Hydroxide                                                                             45.00                                                         Fumed Silica    3.00                                                          Titanium Dioxide                                                                              1.00                                                          ______________________________________                                    

Process: Add Propylene Glycol to the kettle and begin moderate agitationwith a high-speed Cowls disperser blade. Add Calcium Hydroxide slowlyuntil addition is complete. Continue disperser action and add FumedSilica and Titanium Dioxide. Continue for 30 minutes.

An activated relaxer cream is prepared by mixing about 200 to 300 partsof Component I with 20 to 30 parts of Component II. Accurate measuringis not required; the final concentration of active ingredients will bedetermined by the concentration of Lithium Carbonate in Component I.Continue mixing until the color changes from yellow to pink/peachindicating that the pH of the mixture has increased to above pH 12. Therelaxer is ready to use in about 15 minutes after mixing. Moreover, therelaxer can be safely used without fear of irritation for at least oneweek after mixing. Again, this is compared to the two-component relaxersderiving their activity from guanidine hydroxide, which must be usedwithin about four hours after they are mixed.

Example 6

This example represents the preparation of a one-component, no-mixlithium relaxer cream having a stoichiometric excess of CalciumHydroxide relative to Lithium Carbonate.

    ______________________________________                                        Ingredients         Weight Percent                                            ______________________________________                                        Part A:                                                                       Polawax             8.00                                                      Cetyl Alcohol       0.50                                                      Stearyl Alcohol     0.30                                                      PEG-75 Lanolin      2.00                                                      Petrolatum          13.75                                                     Mineral Oil         15.85                                                     Laneth-15           0.40                                                      PEG-24 Hydrogenated Lanolin                                                                       0.20                                                      Ethoxylated Soya Sterol                                                                           1.00                                                      Part B:                                                                       Water               43.00                                                     Propylene Glycol    5.60                                                      Polyol Alkoxy Ester 1.00                                                      Oleth-3             0.30                                                      Lithium Carbonate   2.80                                                      Calcium Hydroxide   5.10                                                      Hydroxypropyl Bis-  0.20                                                      stearyldimonium                                                               Chloride                                                                      ______________________________________                                    

The process was essentially the same as for Example 1; the pH of thecream was 12.9.

When this formulation was used 48 hours after preparation to relax kinkyNegro hair, the results initially were identical to Example 2. However,around two weeks after preparation, this formulation developed a veryhigh degree of irritancy. Two individuals had severe scalp irritationafter only 5 minutes of application. In forearm skin patch tests forirritation, six of seven participants had to remove the aged product ofthis example in less than 15 minutes due to severe burning. In contrast,these same seven participants allowed the products of Examples 1 and 2to remain on their forearms for 30 minutes with no redness orirritation.

Thus, it is clear that the lithium salt must be in excess to thealkaline earth hydroxide to produce a lithium relaxer which has a stablelow-irritancy factor over moderate to long term storage.

Example 7

This example represents the preparation of a one-component "prior art"relaxer deriving its activity from Lithium Hydroxide.

    ______________________________________                                        Ingredients         Weight Percent                                            ______________________________________                                        Part A:                                                                       Polawax             8.00                                                      Cetyl Alcohol       0.50                                                      Stearyl Alcohol     0.20                                                      Petrolatum          22.00                                                     Mineral Oil         15.30                                                     Part B:                                                                       PEG-75 Lanolin      0.40                                                      Laneth-15           0.20                                                      PEG-24 Hydrogenated Lanolin                                                                       1.00                                                      Part C:                                                                       Water               27.30                                                     Propylene Glycol    5.60                                                      Hydroxypropyl Bis-  0.10                                                      stearyldimonium                                                               Chloride                                                                      Part D:                                                                       Lithium Hydroxide Monohydrate                                                                     2.90                                                      Deionized Water     14.20                                                     Part E:                                                                       Calcium Oxide       1.80                                                      Part F:                                                                       Fragrance           0.20                                                      Potassium Coco Hydrolyzed                                                                         0.30                                                      Animal Protein                                                                ______________________________________                                    

Process of making:

1. Weigh out the water and Lithium Hydroxide for Part D and begin mixingin a separate stainless steel pot with a propeller mixer.

2. Weigh out the Part B ingredients in another stainless steel kettleand begin heating to 85° C.

3. Weigh out Part A ingredients in a separate homomixer kettle and beginheating to 85° C. with moderate agitation.

4. Weigh out Part C ingredients in a separate stainless steel kettle andbegin heating to 85° C.

5. When both Part A and Part B reach 85° C., add Part B to Part A andlet mix for 10 minutes.

6. With Part A/B and Part C at 85° C., slowly pump Part C into Parts A/Band let mix for 10 minutes with moderate agitation. After 10 minutes,begin cooling the batch with tap water in the jacket of the kettle.

7. Add Part E to Part D and pre-mix well. (Note: Part D must be fullydissolved before adding to the batch. Part E is to be added to Part Djust before adding to the batch.)

8. When the batch temperature reaches 65° C., shut off the tap watercooling to the kettle and drain the jacket. Add the LithiumHydroxide/Calcium Oxide slurry (Parts D/E) to the batch and continuemixing for 10 minutes with moderate homomixer agitation. (Note: Continueto stir Part D/E with a large metal spatula while adding it to thebatch).

9. Pump the mixture into the scraper kettle and begin cooling to 40° C.with moderate scraper agitation. (Note: The scraper kettle should bechilled with cold water before the batch transfer).

10. Premix the Part F ingredients and add Part F to the batch when thetemperature is 40° C. Continue mixing until the batch is smooth andcreamy or until the batch reaches 35° C.

The pH of the formulations made by this example typically range from 11to 12.

When these prior art relaxers are used to straighten kinky Negro hair bythe process described in Example 1, good straightening results aregenerally obtained. Skin and scalp irritation occurs regularly, withabout the same frequency as aged formulations prepared according toExample 4.

Example 8

This example addresses whether or not the reactive process of thisinvention is broadly applicable to reducing the irritation level of allalkali-metal hydroxide relaxers or just those deriving their activityfrom lithium. Apparently, the reactive process using alkali carbonatesand calcium hydroxide does indeed reduce the irritancy of the resultingrelaxers.

Six relaxers were prepared according to Example 6 except that in fivecases either lithium hydroxide monohydrate, potassium hydroxide,potassium carbonate, sodium hydroxide, or sodium carbonate,respectively, were substituted in molar equivalent amounts for lithiumcarbonate. The Table below shows the specific weight percentsubstitutions and the values of pH of the relaxers.

    ______________________________________                                        Chemical     Formula Wt.                                                                              Mole %   Wt. % pH                                     ______________________________________                                        Lithium Carbonate                                                                          73.89      0.038    2.80  12.9                                   Lithium Hydroxide                                                                          41.94      0.076    3.179 12.15                                  Potassium Carbonate                                                                        138.21     0.038    5.252 13.22                                  Potassium Hydroxide                                                                        65.23      0.076    4.958 13.47                                  Sodium Carbonate                                                                           124.00     0.038    4.712 13.00                                  Sodium Hydroxide                                                                           40.00      0.076    3.04  13.69                                  ______________________________________                                    

Approximately 48 hours after each of the above relaxers were prepared, atest panel of 8 individuals tested their irritancy using a forearm patchtest. The test formulations were applied to different sites on theforearm and left there for 25 minutes (or less if burning occurred). Thefollowing Table summarizes the results.

    ______________________________________                                        Chemical     Stinging/Burning                                                                             Redness                                           ______________________________________                                        Lithium Carbonate                                                                          1 of 8 mild itch/sting                                                                       3 of 8 slight red                                 Lithium Hydroxide                                                                          1 of 8 mild itch/sting                                                                       7 of 8 slight red                                 Potassium Carbonate                                                                        3 of 8 moderate sting                                                                        5 of 8 slight red                                 Potassium Hydroxide                                                                        6 of 8 moderate sting                                                                        6 of 8 very red                                                2 of 8 severe burn                                                                           2 of 8 tissue burn                                Sodium Carbonate                                                                           2 of 8 mild itch/sting                                                                       3 of 8 slight red                                 Sodium Hydroxide                                                                           3 of 8 mild itch/sting                                                                       6 of 8 very red                                   ______________________________________                                    

Example 9

We provide here examples of how alternative lithium salts and alkalineearth metal hydroxides can be used in the present invention.

    ______________________________________                                        Formula:         9A     9B       9C   9D                                      Ingredients      Weight Percent                                               ______________________________________                                        Part A:                                                                       Polawax          8.00   7.00     8.00 8.00                                    Cetyl Alcohol    0.50   0.50     0.50 0.50                                    Stearyl Alcohol  0.30   0.30     0.30 0.30                                    PEG-75 Lanolin   2.00   2.00     2.00 2.00                                    Petrolatum       13.34  12.34    13.35                                                                              14.05                                   Mineral Oil      16.15  14.26    15.66                                                                              16.85                                   Laneth-15        0.40   0.40     0.40 0.40                                    PEG-24 Hydrogenated                                                                            0.20   0.20     0.20 0.20                                    Lanolin                                                                       Ethoxylated Soya 1.00   1.00     1.00 1.00                                    Sterol                                                                        Part B:                                                                       Water            45.40  41.36    32.89                                                                              45.40                                   Propylene Glycol 2.80   2.80     2.80 2.80                                    Hydroxypropyl    0.20   0.20     0.20 0.20                                    Bis-stearyldimonium                                                           Chloride                                                                      Lithium Carbonate                                                                              --     --       --   2.80                                    Lithium Sulfate  4.21   4.21     4.21 --                                      Calcium Hydroxide                                                                              5.10   --       --   5.10                                    Barium Hydroxide --     13.03    --   --                                      Monohydrate                                                                   Strontium Hydroxide                                                                            --     --       18.29                                                                              --                                      Octahydrate                                                                   Part C:                                                                       Fragrance        0.10   0.10     0.10 0.10                                    Potassium Coco-  0.30   0.30     0.30 0.30                                    Hydrolyzed                                                                    Animal Protein                                                                ______________________________________                                    

These formulas were evaluated using a laboratory method to test theirefficacy as hair straighteners, i.e. the Percent Relaxation imparted toNegro hair fibers and the Percent Reversion of these relaxed fibers athigh humidity. The results summarized in the Table below show that threeof the four formulations are highly efficacious. Hair fibers treatedwith Formula 9A (the one prepared with Lithium Sulfate and CalciumHydroxide) had a unacceptable degree of reversion. This is most likelydue a poor yield of active ingredients deriving from the high degree ofsolubility of Calcium Sulfate.

    ______________________________________                                                                   Relaxation,                                        Formula                                                                              OH Source Li Salt   %       Reversion %                                ______________________________________                                        9A     Calcium   Sulfate   97.6 ± 0.7                                                                         16.3 ± 7.4                              9B     Barium    Sulfate   97.8 ± 0.0                                                                         0.4 ± 0.6                               9C     Strontium Sulfate   98.0 ± 0.1                                                                         2.6 ± 3.0                               9D     Calcium   Carbonate 98.2 ± 0.6                                                                         1.8 ± 2.3                               ______________________________________                                    

Example 10

Three "prior art" Lithium Hydroxide relaxer formulations were preparedto determine whether or not the inclusion of Lithium Carbonate in theformulation (as taught in French Patent 1,553,084) would render theformulations less irritating. The specific formulas were as follows:

    ______________________________________                                        Formula:        10A        10B    10C                                         Ingredients     Weight Percent                                                ______________________________________                                        Part A:                                                                       Polawax         8.00       8.00   8.00                                        Cetyl Alcohol   1.20       1.20   1.20                                        Stearyl Alcohol 0.80       0.80   0.80                                        Petrolatum      21.90      22.20  21.20                                       Mineral Oil     16.40      15.10  15.10                                       Part B:                                                                       PEG-75 Lanolin  0.40       0.40   0.40                                        Laneth-15       0.20       0.20   0.20                                        PEG-24 Hydrogenated                                                                           1.00       1.00   1.00                                        Lanolin                                                                       Part C:                                                                       Deionized       27.30      27.30  27.30                                       Water                                                                         Propylene Glycol                                                                              5.60       5.60   5.60                                        Hydroxypopyl Bis-                                                                             0.10       0.10   0.10                                        stearyldimonium                                                               Chloride                                                                      Part D:                                                                       Lithium Hydroxide                                                                             2.90       2.90   2.90                                        Monohydrate                                                                   Deionized       14.20      14.20  14.20                                       Water                                                                         Part E:                                                                       Lithium Carbonate                                                                             --         1.00   2.00                                        pH              12.7       12.6   12.6                                        ______________________________________                                    

All of the formulas were prepared by the process of Example 7. Inforearm patch tests for irritancy, all three of the above formulascaused the same degree of stinging and redness. Thus, the prior artlithium hydroxide relaxers, even with the addition of lithium carbonate,do not produce the successful formulations of the present invention.

Example 11

This example addresses relaxers formulated essentially as Example 10except that polyprotic acids (sulfuric and phosphoric) were used togenerate Lithium Sulfate and Lithium Phosphate in situ. Note that theLithium Hydroxide concentration was increased to provide a molarequivalent amount of LiOH to react with the acids.

    ______________________________________                                        Formula:        11A        11B    11C                                         Ingredients:    Weight Percent                                                ______________________________________                                        Part A:                                                                       Polawax         8.00       8.00   8.00                                        Cetyl Alcohol   1.20       1.20   1.20                                        Stearyl Alcohol 0.80       0.80   0.80                                        Petrolatum      22.00      22.00  22.00                                       Mineral Oil     14.10      14.10  14.10                                       Part B:                                                                       PEG-75 Lanolin  0.40       0.40   0.40                                        Laneth-15       0.20       0.20   0.20                                        PEG-24 Hydrogenated                                                                           1.00       1.00   1.00                                        Lanolin                                                                       Part C:                                                                       Deionized Water 16.99      18.48  16.24                                       Propylene Glycol                                                                              5.60       5.60   5.60                                        Hydroxypropyl Bis-                                                                            0.10       0.10   0.10                                        stearyldimonium                                                               Chloride                                                                      Part D:                                                                       Lithium Hydroxide                                                                             2.90       2.90   2.90                                        Monohydrate                                                                   Deionized Water 14.20      14.20  14.20                                       Part E:                                                                       Lithium Hydroxide                                                                             1.14       5.17   1.70                                        Monohydrate                                                                   Sulfuric Acid   1.37       2.75   --                                          (96.7%)                                                                       Phosphoric Acid --         --     1.56                                        pH              12.3       12.4   12.4                                        ______________________________________                                    

All of the formulas were prepared by the process of Example 7. Inforearm patch tests for irritancy, all three of the above formulascaused the same degree of stinging and redness.

We claim:
 1. A method for the production of a one-component, stable andnon-irritating lithium relaxer formulation comprising:a) providing anoil-in-water emulsion; b) adding a lithium salt and an alkaline earthmetal hydroxide to the emulsion, wherein the lithium salt is in molarexcess to the alkaline earth metal hydroxide and wherein the lithiumsalt is selected from the group consisting of lithium carbonate, lithiumsulfate, and lithium phosphate, and the alkaline earth metal hydroxideis selected from the group consisting of calcium hydroxide, bariumhydroxide, and strontium hydroxide.
 2. A method for the production of atwo-component, stable and non-irritating lithium relaxer formulationcomprising:a) providing an oil-in-water emulsion; b) adding an alkalineearth metal hydroxide to the emulsion; c) providing a lithium salt as anactivator for mixing with the emulsion to form the relaxer formulation;wherein the lithium salt is in molar excess to the alkaline earthhydroxide in the relaxer formulation and wherein the lithium salt isselected from the group consisting of lithium carbonate, lithiumsulfate, and lithium phosphate, and the alkaline earth metal hydroxideis selected from the group consisting of calcium hydroxide, bariumhydroxide, and strontium hydroxide.
 3. A method for the production of atwo-component, stable and non-irritating lithium relaxer formulationcomprising:a) providing an oil-in-water emulsion; b) adding a lithiumsalt to the emulsion; c) providing an alkaline earth hydroxide as anactivator for mixing with the emulsion to form the relaxer formulation;wherein the lithium salt is in molar excess to the alkaline earth metalhydroxide in the relaxer formulation and wherein the lithium salt isselected from the group consisting of lithium carbonate, lithiumsulfate, and lithium phosphate, and the alkaline earth metal hydroxideis selected from the group consisting of calcium hydroxide, bariumhydroxide, and strontium hydroxide.
 4. A method of straightening hair,said method comprising:a) contacting the hair with an aqueouscomposition comprising the reaction products formed by reacting, in anaqueous medium, a lithium salt and an alkaline earth metal hydroxide,wherein the lithium salt is in molar excess to the alkaline earth metalhydroxide and wherein the lithium salt is selected from the groupconsisting of lithium carbonate, lithium sulfate, and lithium phosphate,and the alkaline earth metal hydroxide is selected from the groupconsisting of calcium hydroxide, barium hydroxide, and strontiumhydroxide, b) maintaining the hair under tension, and c) removing saidcomposition from the hair.
 5. The method of claim 4 wherein the lithiumsalt is lithium carbonate.
 6. The method of claim 4 wherein the alkalineearth metal hydroxide is calcium hydroxide.
 7. A method of straighteninghair, said method comprising:a) providing an oil-in-water emulsion; b)adding a lithium salt and an alkaline earth metal hydroxide to theemulsion to form a hair straightening composition, wherein the alkalineearth metal hydroxide is in molar excess to the alkaline earth hydroxideand wherein the lithium salt is selected from the group consisting oflithium carbonate, lithium sulfate, and lithium phosphate, and thealkaline earth metal hydroxide is selected from the group consisting ofcalcium hydroxide, barium hydroxide, and strontium hydroxide; c)applying said composition to the hair which is maintained under tensionfor the period of time necessary to accomplish the straightening of thehair; and d) removing the composition from the hair.
 8. A kit for use instraightening hair comprising a first ingredient and a secondingredient, which are disposed in separate containers and which arecombined to produce the hair straightening composition;a) wherein thefirst ingredient is an oil-in-water emulsion which comprises an alkalineearth metal hydroxide, and b) wherein the second ingredient is anactivator which comprises a lithium salt, wherein the lithium salt is inmolar excess to the alkaline earth metal hydroxide in the hairstraightening composition and wherein the lithium salt is selected fromthe group consisting of lithium carbonate, lithium sulfate, and lithiumphosphate, and the alkaline earth metal hydroxide is selected from thegroup consisting of calcium hydroxide, barium hydroxide, and strontiumhydroxide.
 9. A kit for use in straightening hair comprising a firstingredient and a second ingredient, which are disposed in separatecontainers which are combined to produce the hair straighteningcomposition;a) wherein the first ingredient is an oil-in-water emulsionwhich comprises a lithium salt, and b) wherein the second ingredient isan activator which comprises an alkaline earth metal hydroxide, whereinthe lithium salt is in molar excess to the alkaline earth metalhydroxide in the hair straightening composition and wherein the lithiumsalt is selected from the group consisting of lithium carbonate, lithiumsulfate, and lithium phosphate, and the alkaline earth metal hydroxideis selected from the group consisting of calcium hydroxide, bariumhydroxide, and strontium hydroxide.